Method and apparatus for clamping planks,boards,poles,pipes,and the like,to pile drivers and pulling devices

ABSTRACT

A clamping arrangement, and a method of operation thereof, for clamping a work member to a reciprocable driving mass. The clamp arrangement has a pair of jaws which are urged toward each other by fluid operable means which is energized by a pump which has a piston that is actuated to draw fluid from a reservoir by movement of the mass and is actuated to supply fluid to the fluid operable means by a spring.

United States Patent [1 1 [1 11 3,708,151

Schulin [4 1 Jan. 2, 1973 [54] METHOD AND APPARATUS FOR [56] References Cited CLAMPING PLANKS, BOARDS, POLES, PIPES, AND THE LIKE, TO FILE UNITED STATES PATENTS DRIVERS AND PULLING DEVICES 3,217,545 10/1966 Martin "24/230 AL Inventor: Schulin Fellbach, m y 3,414,314 12/1968 Martin .1 ..294/]03 [73] Assignee: Wacker Werke KG, Munich, Gerprimary Simpson many Attorney-Walter Becker [22] Filed: Dec. 10, 1970 [21] Appl. No.: 96,867 [57] ABSTRACT A clamping arrangement, and a method of operation thereof, for clamping a work member to a reciproca- [30] Foreign Application Priority Dam ble driving mass. The clamp arrangement has a pair of Dec. 12, 1969 Germany ..P 19 62 318.8 jaws which are urged toward each other by fluid operable means which is energized by a pump which :LtS-CCll. has a piston that is actuated to draw from a resetll b h t t 58 Field of Search .254/133, 93; 24/2635, 230 AL, y movement of t e mass and ac 0 24/230 AN, 263 PJ; 294/103 supply fluid to the fluid operable means by a spring.

19 Claims, 2 Drawing Figures I i! l l l l l METHOD AND APPARATUS FOR CLAMPING PLANKS, BOARDS, POLES, PIPES, AND THE LIKE, TO PILE DRIVERS AND PULLING DEVICES The present invention relates to a method of and apparatus for clamping planks, boards, poles, pipes, and the like, to pile drivers and pulling devices.

Hydraulic clamping pliers or holders for pile driving and pulling devices have become known by means of which the article to be driven or pulled, for instance, steel profiles, sheet piles or piles are clamped fast to the pile driving or pulling device. Such clamping holders are employed primarily in connection with vibration pile drivers or hammers. The pressure of the hydraulic fluid for actuating such clamping devices, i.e., for producing the clamping pressure, is produced manually or by foot pumps or by motor driven pumps. Such pumps are located either in the vicinity of the driving or pulling device on theground. Such pressure also is produced by motor pumps which are mounted on the driving or pulling device.

When a device is involved which utilizes a hydraulic pump located on the ground, the hydraulic conduit, for instance, the high-pressure hose, which leads to the driving or pullingdevice interferes with the working of the device on the building site. This is due primarily to the fact that the hose in tightened condition is rather stiff and its flexibility is rather limited as a result thereof. Moreover, such hose is exposed to the danger of being damaged, in view of the relatively rough building site operation and the traffic of the building site. This may cause accidents because in such instances the clamping connection may be disengaged. A further difficulty consists in the breaking of the hoses or hose connections in view of the acceleration during the ramming and pulling operation.

The cost for an electromotor driven hydraulic pump on the ramming and pulling device and even the passing of an electric control line in upward direction pays only with large machines and only when such machines are driven electrically anyhow. Ramming and pulling devices which are driven directly by internal combustion engines do not offer basic conditions for electrically driven pressure pumps.

It is, therefore, an object of the invention to provide a method and apparatus for driving and pulling devices operated directly by internal combustion, which without interfering conduits from the pump to the apparatus as, for instance, control lines, can be driven without the aid of foreign power sources such as electric current or compressed air.

These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

, FIG. 1 illustrates an embodiment of ,a clamping device according to the invention as installed in a driving or pulling device.

FIG. 2 illustrates an embodiment of an automatic pump occupying its intermediate position of operation.

The present invention is'characterized primarily in that the oscillating pushing mass actuates a pump which draws a pressure medium from a pressure medium reservoir and conveys said pressure medium through valves and control lines to clamping bodies movably arranged on the working implement. The

oscillating pushing mass acts upon a cylinder which is resiliently arranged and operates as pump. This cylinder communicates through control lines and valves with a chamber containing a pressure medium. The cylinder is adapted to act by way of a fixedly arranged piston, valves and control pistons through a pressure medium upon a movably arranged clamping The cylinder may be designed as a stepped cylinder and may be movable by the oscillating pushing mass against the thrust of a spring.

The discharge valve is held by means of two serially arranged pressure springs. Between said two pressure springs, a control piston is movably arranged which may be provided with a calibrated bore. The spring constant of the two pressure springs may be different. The pressure medium reservoir may be so designed that a slight overpressure prevails therein with regard to the atmosphere. The important advantage of the invention is seen in the fact that an additional expensive arrangement on the driving or pulling device for clamping the article to be pulled or driven will not be necessary. The clamping device is advantageously so designed that special control lines are not necessary and the clamping device will, in response to the start of the driving or pulling device close automatically. This means it will automatically clamp the boards, or the like, and will automatically release such boards, or the like automatically after the device has been stopped.

The automatic pump is designed so that during the driving and also with power strokes in downward direction, and furthermore also during pulling action with power strokes in upward direction the same will automatically clamp in the respective subject as, for instance, a board. Advantageously, the automatic pump, during the entire driving or pulling operation, in other words, during the operation of the device, will remain in pumping readiness in order to hold the required clampingpressure and to cover any possible leakage. In spite of the continuous low pressure maintaining pumping action, the maximum pressure is limited without the necessity of providing a pressure limiting control or overflow valve. As a result thereof, unnecessary heating up of the pressure fluid will occur and parts subject to wear and disorder will be avoided.

A further advantage of the invention consists in that the automatic pump is so designed that it will also function properly when the oscillating pushing mass carries out uneven strokes, in other words, when the reversing points or dead center points are not always located at the same points.

Referring now to the drawings in detail, the invention will be described in connection with the installation of a driving or pulling device, the oscillating pushing mass of which, is driven by an internal combustion engine. Such engine may, for instance, be a driving machine of the type of a vibration tamper. The installation may also be effected in a driving or pulling device, the pushing rammer or driver mass of which is represented, for instance, directly by the piston of a cylinder of an air cushioned free piston-type engine.

More specifically, the flange 1 of a driving engine (not further illustrated), has arranged thereon the driver mass 2 which is slidable in the body 3. The arrangement furthermore comprises a return spring 4 which may also be termed a supporting spring which softly supports the driver mass 2, including the driving engine, on the post to be driven. When the device acts as a driving device, spring 4 will be omitted. An exchangable clamping jaw 5 is mounted on the body 3. A clamping jaw 6 opposite the preloaded pressure spring 7 is movably arranged in the body 3. Sealing members 8 may be provided between the clamping jaws 6 and the body 3. The automatic pump 10 communicates with the pressure medium reservoir 9 through a control line 115. The automatic pump illustrated in greater detail in FIG. 2 represents an embodiments to which the invention is not limited. The pump of FIG. 2 comprises a stepped piston 101, a stepped cylinder 102 and a pressure spring 103. A suction valve 104 and an outlet valve 105 are installed in said stepped piston. Between the pressure springs 11] and 112 of said outlet valve 105 there is a control piston 106, floatingly arranged. Sealing means 107 and 108 are provided between the stepped piston 101 and the stepped cylinder 102. The following sets forth details concerning how the pump-is actuated. The lower end of the mass 2 engages upon the face side of the pump 10 (FIG. 1). The same pump 10 (FIG. 1) is drawn out greatly in FIG. 2. The hollow space or chamber of the parts 2 and 3 (FIG. 1) is occupied neither by liquid nor gas. There is also no seal provided to the outside.

By way of an axial shifting by part 102 (FIG. 2) downwardly as introduced by way of engagement of part 2 (according to FIG. 1), there arises in the pump chamber 116(FIG. 2) a change in volume, namely, a volume enlargement. Thereby oil can be suctioned out of the storage container by way of the valve 104 through the conduit or passage means 1 14/115.

Correspondingly in FIG. 2 in the passages 115 and 114 the oil stand or level would be dotted for illustration as in the supply or storage container.

After unloading or relief of the cylinder 102 there is lifting of the part 2 according to FIG. 1 and the pressure spring 103 unloads or relaxes (removal of stress), again lifts the part 102 into the original position and thereby there occurs a volume reduction in the pump chamber 116. Thereby the liquid is pressed by way of the discharge valve 105, the bore 113 into the conduit 110 and from there into a chamber not designated separately below the pump 10 (FIG. 1).

With a ram the impact occurs from above toward the bottom. Since the spring 4 (FIG. 1) in this case hinders the engagement of the part 2 upon the part 3, at least moreover would considerably dampen, the spring 4 is to be removed during ramming (FIG. 1). During pulling procedure, the impact is necessary in opposite direction. When however a normal vibration stamper gives off the impact downwardly from the construction and from the force of gravity, then a pulling procedure would not be possible. Here the inserted spring 4 has the object to store the introduced energy and after the lifting off of the upper mass to lift the parts 1 and 2 with high speed upwardly and the introduced energy is then given off by way of engagement upon the part 3.

By way of the differing spring constants of the pressure spring 111 and 112, whereby the spring 111 is stronger, the control piston 106 is pressed upwardly and the control bore 109 becomes free. This condition is not illustrated in FIG. 2. In FIG. 2 there is designated the position of the control piston 106 during operation. In reset position there is thus possible that oil can flow back from the clamping jaw cylinder 6 into the storage container but also can again be suctioned. This is particularly important primarily with a material to be clamped when for instance with a plank brushes form (staved plank) and these must be traversed with the jaws 5 (large opening width, small clamping width).

The function of the arrangement according to the invention is as follows:

The clamping jaw 6 is, by the pressure of spring 7, pressed against the toothed clamping jaw 5 and has its end face first in direct engagement with the toothed surface of the clamping jaw 5. When the driving or pulling device hits, for instance, a bulkhead-steel profile, the clamping jaw 6 will, in view of the inclined introducing surfaces on the clamping jaw 5 and clamping jaw 6 be displaced against the thrust of spring 7 into the cylinder of the body 3. A portion of the pressure medium in the cylinder chamber will be pressed back into the supply chamber or reservoir 9. The channel 109 leading to the cylinder chamber and reservoir 9 is always open, during the standstill of the device. The clamping jaw 6 will, after touching down or setting, directly engage the profile to be pulled. This is the case also when during thetraveling inbound or moving-in,

, when the pulling device touches down or sets, a brush,

bur or finwiper at the end face of the post or steel profile was moved over or traversed. In view of the above mentioned passage 109 which is open at the standstill of the device, the clamping jaw 6 is able after moving over a possible brush, again to receive pressure medium from the reservoir. This mode of operation of this design has the advantage that the pump which is designed for smaller deliveries of high pressure does not have to pump for a longer period of time prior to the clamping process proper in order to bring the piston into its starting position proper for the clamping operation, but is able to carry out the clamping action immediately by means of a few pumping strokes.

When starting the driving or pulling device, the movable stepped cylinder 102 is pressed against the thrust of spring 103 downwardly by a short push of the ram mass oscillating in vertical direction. By the abutment of the stepped cylinder, the suction operation of the pump is brought about, whereas the pumping operation proper, the delivery of the pressure fluid into the cylinder being effected by the pressure spring 103. During the first strokes of the oscillating ram mass following the starting of the device, the stepped cylinder will carry out approximately the fully feeding strokes until the required clamping pressure has been realized. Subsequently, the pump by itself stops delivering because the spring selected in conformity with the active step cross section of the pump will no longer be able to press the movable cylinder upwardly against the fluid pressure. Thus, a pressure limiting value (overpressure discharge valve), as required with automatic pumps will no longer be necessary.

The spring of the discharge valve 105 comprises two serially arranged pressure springs 111 and 112, between which there is inserted an easily movable control piston 106, which forms the control valve spool. During the standstill of the operation, i.e., when no pressure fluid is delivered, this control piston 106 is in equilibrium with the two pressure springs 111 and 112 and stands upwardly to such an extent that the control bore 109 is not covered thereby, either having an over dimensioned but fixed bearing guide play or and having a calibrated bore. Pressure fluid delivered by the pump can pass through this bore or through this mantle gap into the passage 110 and to the cylinder chamber. In view of the pressure drop which during a pressure fluid supply in operation has become effective in the control piston 106, the latter is pressed downwardly thereby closing the control bore 109.

The pressure fluid volume delivered by the pump is thus able to produce the required clamping pressure. This automatic pump will first, without particular pumping operation, maintain the required clamping pressure because spring 103, which has deliberately been designed with a relatively flat characteristic, is loaded. Leakage losses, and the like, are first covered or made up by the stored work of the pressure spring 103. Beyond this, the pump remains in continuous readiness to deliver, to scoop up and to pump. This occurs when the stepped cylinder 102 has moved upwardly to such an extent that cylinder 102 is, by the ram mass 2, continuously oscillating during the operation, actuated again to perform a suction stroke and pushed downwardly for clamping the pressure spring 103. For the function of the above described type it is irrelevant whether the reversing points, i.e., the lower dead center points of the ram mass 2 are always at the same level or whether individual protruding strokes which extend particularly far and are carried out by the oscillating ram mass 2 will abut or load the stepped cylinder 102.

This design, according to the invention, also makes it possible to employ the automatic pump and thus the entire clamping device for clamping the pole during the drawing operation as well as when driving with posts, or the like. The last mentioned arrangement hasthe advantage that, for instance, the bulkhead wall-steel profiles have their upper end face protected against breakage.

If, during the operation or after the device has been stopped, no pressure fluid delivery takes place any longer. The pressure drop above and below the control piston 106 balance each other through the calibrated small bore 113. The control piston 106 will have'the tendency to adjust itself in conformity with the force balancing weight of the two springs 1 11 and 112 and to move upwardly. In view of this movement of the controlpiston in upward direction, it will, from a certain stroke performed by the control piston 106, gradually free the control bore 109 so that pressure fluid can escape from the pressure into the suction chamber. When this occurs, the pump will immediately deliver pressure fluid whereby the control piston 106 will again be displaced to its closing position. In practice, the control piston 106 always remains close to the control limit so that continuously small leakage losses are to be replaced by the pump. Moreover, in practice, due to the accelerating pushes exerted during the driving or pulling operation upon the body 2 and thus upon the stepped piston 101 arranged therein, slight relative movements will occur between the control bore 109 in the stepped piston 101 and the control piston 106. In order to keep the effect of these relative movements upon the control operation rather low, the control edge of the control piston 106 is not sharp edged, but is conical or inclined according to any practical curve shape.

When, after stopping the device, the delivery of pressure fluid also stops, the control piston 106 will completely free the cross section of the control bore 109. This is due, in view of the displacement by the lower spring 111 which is under increased load, so that the clamping pressure completely disappears and the driving or pulling device can be lifted from the article to be pulled.

When the clamping device is designed as a hydraulic clamping device, it is advantageous to maintain pressure fluid reservoir 9, for instance, by means of a resilient piston, under continuous slight overpressure. In this way it will be realized that, forinstance, when withdrawing the device, in other words, when it does not work, air can enter the control lines. In this way, the working device will be location-nonsensitive, which means it may also laterally be placed on the ground without air being able to enter the control lines and the pump. The compressability of air would otherwise oppose a fast attraction of the clamping device.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawings, but also comprises any modifications within the scope of the appended claims.

What is claimed is:

l. A clamping arrangement for clamping a work member to a reciprocable driving mass which comprises: a pair of opposed jaws adapted to receive the workpiece therebetween and supported by said mass, motor means operatively associated with said jaws and energizable for urging said jaws toward each other, power developing means supported by said mass and actuated in response to reciprocation of said mass and operatively connected to said motor means to supply energy thereto when actuated.

2. A clamping arrangement according to claim 1 in which said motor means comprises fluid operable means associated with at least one said jaw, said power developing means comprising a pump having a discharge side connected to said fluid operable means, and a fluid reservoir carried by said mass and connected to the inlet side of said pump, said pump comprising a piston reciprocable in the same direction as said mass. I

3. A clamping arrangement-according to claim 2 which includes a body reciprocable on said mass and having said jaws and said pump and reservoir mounted thereon. g

'4. A clamping arrangement according to claim 3 in which said pump piston is adapted to be engaged and actuated in one direction by said mass when the mass and body move relatively in one direction, and a spring I acting on said piston to move it in the other direction.

6. A clamping arrangement according to claim 4 in which said piston is sleeve-like, a cylindrical element on said body on which said piston reciprocates, and a pumping chamber formed by said piston and cylindrical element. 0

7. A clamping arrangement according to claim 6 in which the bore through said piston has a step therein so the bore has two different diameters.

8. A clamping arrangement according to claim 6 in which said cylindrical element is stepped and has a portion fitting each diameter of the bore in said piston.

9. A clamping arrangement according to claim 6 in which the bore in the piston and the cylindrical element are stepped so as to have shoulders which face each other thereby to define a pumping chamber which expands and contracts as said piston reciprocates relative to said cylindrical element, a first passage in said cylindrical element connecting said pumping chamber to said reservoir and a first check valve therein opening toward said chamber, a second passage in said cylindrical element connecting said chamber to said fluid operable means and a second check valve therein opening away from said chamber, and a control valve between said fluid operable means and said reservoir for releasing pressure from said fluid operable means.

10. A clamping arrangement according to claim 9 which includes two springs in series on the downstream side of said second valve biasing said second valve toward closed position.

11. A clamping arrangement according to claim 10 in which the spring constants of said springs differ from each other.

12. A clamping arrangement according to claim l1 in which said control valve is disposed between said springs.

13. A clamping arrangement according to claim 12 which includes a restricted passage interconnecting the opposite ends of said control valve.

14. A clamping arrangement according to claim 12 in which said control valve interrupts communication between said fluid operable means and said reservoir during the supply of pressure fluid to said fluid operable means by said pump.

15. A clamping arrangement according to claim 1 in which comprises means to maintain a predetermined minimum pressure on the fluid in said reservoir.

16. A clamping arrangement according to claim 15 in which said means comprises a spring loaded piston.

17. A clamping arrangement according to claim 2 which includes spring means biasing said jaws toward each other.

18. The method of clamping a reciprocable mass to a work member to be moved thereby which comprises, engaging said work member by opposed jaws carried by said mass, and driving said jaws toward each other by energy derived from the reciprocation of said mass.

19. A method according to claim 18, in which said energy is fluid pressure energy and is developed by pumping means actuated in response to reciprocation of said mass. 

1. A clamping arrangement for clamping a work member to a reciprocable driving mass which comprises: a pair of opposed jaws adapted to receive the workpiece therebetween and supported by said mass, motor means operatively associated with said jaws and energizable for urging said jaws toward each other, power developing means supported by said mass and actuated in response to reciprocation of said mass and operatively connected to said motor means to supply energy thereto when actuated.
 2. A clamping arrangement according to claim 1 in which said motor means comprises fluid operable means associated with at least one said jaw, said power developing means comprising a pump having a discharge side connected to said fluid operable means, and a fluid reservoir carried by said mass and connected to the inlet side of said pump, said pump comprising a piston reciprocable in the same direction as said mass.
 3. A clamping arrangement according to claim 2 which includes a body reciprocable on said mass and having said jaws and said pump and reservoir mounted thereon.
 4. A clamping arrangement according to claim 3 in which said pump piston is adapted to be engaged and actuated in one direction by said mass when the mass and body move relatively in one direction, and a spring acting on said piston to move it in the other direction.
 5. A clamping arrangement according to claim 4 in which said piston draw fluid from said reservoir when moved in said one direction and displaces fluid to said fluid operable means when moved in said other direction.
 6. A clamping arrangement according to claim 4 in which said piston is sleeve-like, a cylindrical element on said body on which said piston reciprocates, and a pumping chamber formed by said piston and cylindrical element.
 7. A clamping arrangement according to claim 6 in which the bore through said piston has a step therein so the bore has two different diameters.
 8. A clamping arrangement according to claim 6 in which said cylindrical element is stepped and has a portion fitting each diameter of the bore in said piston.
 9. A clamping arrangement according to claim 6 in which the bore in the piston and the cylindrical element are stepped so as to have shoulders which face each other thereby to define a pumping chamber which expands and contracts as said piston reciprocates relative to said cylindrical element, a first passage in said cylindrical element connecting said pumping chamber to said reservoir and a first check valve therein opening toward said chamber, a second passage in said cylindrical element connecting said chamber to said fluid operable means and a second check valve therein opening away from said chamber, and a control valve between said fluid operable means and said reservoir for releasing pressure from said fluid operable means.
 10. A clamping arrangement according to claim 9 which includes two springs in series on the downstream side of said second valve biasing said second valve toward closed position.
 11. A clamping arrangement according to claim 10 in which the spring constants of said springs differ from each other.
 12. A clamping arrangement according to claim 11 in which said control valve is disposed between said springs.
 13. A clamping arrangement according to claim 12 which includes a restricted passage interconnecting the opposite ends of said control valve.
 14. A clamping arrangement according to claim 12 in which said control valve interrupts communication between said fluid operable means and said reservoir during the supply of pressure fluid to said fluid operable means by said pump.
 15. A clamping arrangement according to claim 1 in which comprises means to maintain a predetermined minimum pressure on the fluid in said reservoir.
 16. A clamping arrangement according to claim 15 in which said means comprises a spring loaded piston.
 17. A clamping arrangement according to claim 2 which includes spring means biasing said jaws toward each other.
 18. The method of clamping a reciprocable mass to a work member to be moved thereby which comprises, engaging said work member by opposed jaws carried by said mass, and driving said jaws toward each other by energy derived from the reciprocation of said mass.
 19. A method according to claim 18, in which said energy is fluid pressure energy and is developed by pumping means actuated in response to reciprocation of said mass. 